BEIRUT (AP) — With President Barack Obama weighing the issue, increasingly desperate Syrian rebels are pressing the U.S. and its allies to send weapons to even their odds now that Lebanon’s powerful Hezbollah guerrillas are fighting alongside the regime.

The U.S. and its allies so far have refused to send lethal aid to the rebels in part because of fears that the arms could fall into the hands of Sunni extremist groups that have joined the fight against President Bashar Assad.

Moderate opposition leaders have stepped up efforts to turn that argument around, saying Western inaction will deal a blow to their leadership and let al-Qaida-linked militants take the forefront in the rebellion or hand victory to Iran and Hezbollah, a Shiite militant group. They’re hoping the newly visible role of Hezbollah and the fall of the strategic town of Qusair to regime forces will spur the U.S. and other countries to send weapons.

Ahmed Ramadan, a member of the main Western-backed opposition group, the Syrian National Coalition, said the failure to supply weapons and ammunition to moderate forces within the rebels’ Free Syrian army will let radical forces take the lead.

“Who is the U.S. denying weapons to? Everyone,” he said. “This punishes the moderate forces, not the radical ones, because the radical forces continue to find armament through their own means,” he said.

The Obama administration has been alarmed by the Assad regime’s rapid military advances, but U.S. officials said those closest to the president are still split on whether to begin providing Syria’s armed opposition with weapons or to consider more drastic steps such as using U.S. airpower to ground Assad’s gunships and jets. The officials spoke on condition of anonymity because they weren’t authorized to speak publicly on private talks being held Wednesday on the issue.

Burhan Ghalioun, a prominent Paris-based Syrian opposition leader, said he and his comrades have been trying to convince U.S. officials that it’s time to put an end to the tragedy in Syria by empowering moderate rebels. He warned an Assad victory also would mean more sway in Syria for Hezbollah and its Iranian backers.

“The U.S. now faces a real test that has to do with its credibility,” he said in a telephone interview. “Are they going to let Syria become an Iranian protectorate? This is what it boils down to,” he said.

“Their hesitation and reluctance is prolonging the war and giving false illusions that Bashar Assad can win the war,” he added.

Opposition leaders stepped up their outreach after the fall of Qusair, a key western town near the border with Lebanon. Hezbollah fighters openly joined the fight in Qusair, helping propel Assad’s forces to victory. The group’s leader, Sheikh Hassan Nasrallah, has vowed to fight to help secure a victory for the Syrian regime.

Gen. Salim Idris, the main rebel military commander in the Free Syrian Army, has repeatedly pleaded for Western anti-tank and anti-aircraft missiles, saying the rebels’ weapons were no match for the Syrian regime’s modern tanks and warplanes.

Any military assistance to the rebels would likely be funneled through Idris’ council, according to U.S. officials.

Syrians complain that by denying Idris the weapons, the West has effectively undermined the commander’s authority on the ground.

“Rebel loyalty is going to be with whoever is providing them with the guns and ammunition, and so far it’s not Idris who is doing that,” said Amr Al Azm, a U.S.-based Syrian activist and professor at Shawnee State University in Ohio.

Bassam al-Dada, an official with the Free Syrian Army, expressed skepticism that the U.S. would start providing weapons, and said even if it does the amount is unlikely to be sufficient to change the situation on the ground.

“If it happens, it will likely be small, insignificant aid that will in fact create problems between the military leadership and the rebels on the ground, who will think weapons were coming in when in fact they are not,” he said.

Zeineddine al-Shami, a media coordinator for the First Brigade in the Free Syrian Army in Damascus, said radical groups such as Jabhat al-Nusra represent a small percentage of the fighters on the ground but their impact has been felt because of tactics, including suicide bombings.

“We won’t need (suicide bombers) if we have artillery or rockets” or more sophisticated weaponry,” he said. “If we don’t, the spirit of Nusra will prevail.”